I also had the Helix feeder and my horse was pretty rough with it. I eventually took it out of her stall as she was starting to crack it and I didn’t want her to destroy it. She’s not rough to the point where she decimates the SmartPak hay nets though, I have one going on 6 years which has held up better than the Kiwi Helix feeder. IMO if the horse has gone through the SmartPak net then I would be hesitant about buying a Helix feeder unless you can buy one used since they’re pricy new.
For the Portagrazer, could you put one of those huge salt licks in the bottom of it? One that weighs like 30ish lbs or more to try and discourage him from bouncing around the stall? This was the issue I had with the Kiwi Helix feeder actually, she spent all night throwing and flipping it which wasn’t great for her neck. The Portagrazer would probably work if you could weigh down the bottom of it!